Fluid injection device



Aug. 4, 1959 c. A. TEICHERT 2,898,051

FLUID INJECTION DEVICE Filed Aug. 15, 1957 2 Sheets-Sheet 1 H w W/ M ,v]

W -K M /z INVENTOR.

ATTORNEY.

FLUID INJECTION DEVICE Conrad A. Teichert, Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 15, 1957, Serial No. 678,370

7 Claims. (Cl. 239-533) This invention relates to pressure fluid injectors, and particularly those having the pump combined therewith as a unit for the injection of liquid fuel into the cylinders of internal combustion engines, and wherein the injection is effected in successive stages.

Among the principal problems associated with such prior injectors are that the very high injection pressures developed impose considerable strain and wear on the component parts ofthe pump, the pump driving mechanism, valve parts, etc., and the engine power devoted to their operation is likewise considerable. Also, there is a constant striving in the industry to improve fuel atomization for more eflicient combustion over a wide range of engine speeds. The present invention effects important improvements in both the aforementioned respects by providing an injector which delivers the fuel charge in successive stages at substantially different rates and at pressures controlled to not exceed values required for good atomization.

In general, the improvements are accomplished by controlling the opening of the first stage injection spray holes with a valve member movable in response to increasing fluid pressure, and then opposing further such movement of the valve member in opening the second stage injection holes by application of the fluid pressure to the valve as a biasing force.

A better understanding of the invention will be had from the following description of one preferred embodiment, having reference to the drawings wherein:

Figure 1 is a view partly in longitudinal section and partly in elevation of my improved injector incorporated in a unit type fuel injector pump mounted on an internal combustion engine.

Figure 2 is an enlarged fragmentary view similar to Figure 1, showing the injector parts and lower portion of the pump in greater detail.

Referring first to Figure 1, there is shown a portion of an internal combustion engine cylinder head 1 whose inner wall 2 defines the usual combustion chamber. Mounted on the cylinder head and extending therethrough into the combustion chamber of the engine is a unit type fuel injector pump assembly 3 comprising a pumping chamber 4 into which a plunger 5 is adapted to be reciprocated by an engine driven rocker 6 and plunger return spring 7 in conventional manner. Fuel from a transfer pump (not shown) or equivalent means is supplied through a fitting 8 and suitable connecting passages, e.g., 9, to an annular fuel receiving chamber 10 surrounding a bushing 11 which forms the cylinder of the pumping chamber 4. Fuel inlet and by-pass ports 12, 13 connecting the chambers 10 and 4 are controlled by the inner end 14, relief groove 15 and internal passage 16 of the plunger during its reciprocation such that a sufficiently high fuel pressure for injection is developed in the pumping chamber 4 during each downward stroke of the plunger.

Directly below the pumping chamber 4 is located the injection nozzle assembly 17, unitarily associated with 2,898,051 Patented Aug. 4, 1959 the pump structure by a common supporting shell 18. Extending through the lower end of this shell 18, as best seen in Figure 2, is the nozzle tip 19 of an injector valve body 20. The valve body 20 is clamped between an inturned flange 21 at the lower end of the shell 18 and the lower end of the bushing 11 by an intermediate cage and guide piece 22. The valve body 20 has a bore 23 open at its upper end and terminating at its lower end in an annular enlargement 24 and lower fuel cavity 25. The cavity 25 is closed to the engine combustion chamber except for one or more circumferentially spaced first stage fuel injection spray holes 26, and the entrance to this cavity is defined at its upper end by a valve seat 27. Connecting the bore 23 with the exterior of the valve body and the combustion chamber are one or more second stage fuel injection ports 28 whose outer ends are enlarged as shown to effect the desired direction and spread of the fuel spray. An injection fuel inlet passageway is provided between the pump chamber 4 and the valve body enlargement 24. This passageway comprises a plurality of openings 29 through a stop member 30 in the upper end of the guide piece 22, a longitudinal passage 31 through the latter and a connecting longitudinal passage 32 through the valve body 20.

Slidably fitting the valve body bore 23 is a piston valve 33 having a reduced lower end portion 34 engageable with the seat 27 to close off the cavity 25 from the bore. The reduction between this portion of the piston valve and the main body thereof provides an annular shoulder surface 35 which is in constant communication with the injection fluid inlet pressure supplied from the pumping chamber, and this shoulder 35 is located substantially below the second stage orifice 28 when the piston valve is seated, such that substantial opening movement of the piston valve must occur after its portion 34 leaves its seat before the second stage orifices 28 are uncovered. Such opening movement of the piston valve is opposed by resilient means, shown in the form of a compression spring 36 which is located in a pocket 37 provided in the lower end of the guide piece 22. The force of the spring 36 is transmitted to the piston valve by a push rod 38 whose upper end is adapted to project through an opening in the guide piece. Slidably fitted in an enlargement of this latter opening is a plunger member 39 whose upper end is exposed to the injection fluid inlet pressure in the passage 31. The plunger member 39 normally rests on a stop shoulder 40, and when the piston valve is seated there. is a substantial operating gap or clearance A between the lower end of the plunger member 39 and the upper end of the push rod 38. Also when thus seated, the plunger member has a substantial operating clearance B between its upper end and the stop member 31).

During operation, as fuel pressure is built up in the pumping chamber 4 it is also applied to the piston valve shoulder 35, but the piston valve remains closed on its seat 27 until the fuel pressure force overcomes the seating force of the spring 36. When this happens the piston valve rises to allow fuel to enter the cavity 25 and pass through the first stage injection holes 26 to the engine combustion chamber. At this point the area represented by the piston valve portion previously engaged with the seat 27 is then also subjected to injection fluid inlet pressure, resulting in considerable additional elevating force applied to the piston valve and causing it to move further upward in the opening direction. In advance of the second stage orifices being uncovered by the piston valve shoulder 35, however, the clearance A between the push rod and the plunger member 39 is taken up. Thus, there is substantial lost motion of the piston valve relative to the plunger member 39 in rising from its position shown to that at which it picks up the member 39, the amount of this lost motion being equal to the clearance A. Continued further opening movement of the piston valve is thence further opposed by the injection fluid inlet pressure acting downwardly against the upper end surface of the plunger member 39. The effective area of this surface (cross sectional area of the member 39) exposed to such fuel injection pressure is made less than that (combined pressure reacting areas of the shoulder 35 and seating portion 34) of the piston valve, so that a net differential force is applied to open the piston valve against the increasing biasing force of the spring 36. Upon sufficient further build-up of the inlet pressure from the pumping chamber, therefore, the piston valve uncovers the second stage orifices 28 to augment the charge being delivered to the engine via the first stage orifices 26.

Thus, up to a predetermined injection pressure,-injection takes place only through the first stage spray holes or orifices 26. Above this predetermined pressure the second stage holes 23 add their effective spray area to reduce injection pressures in the system. Because of this fact approximately 50% of the injector fuel capacity may be handled through the first stage comprising approximately 50% of the spray hole area of a conventional injection system with the resulting high atomization and combustion efliciency. By properly balancing design variables such as effective spray hole areas, pressure responsive areas of the piston vave 33 and plunger 39, and rate of the spring 36, a multitude of performance values can be created to suit individual conditions.

For example, employing a spring 36 having a rate of 569 lb./in., a piston valve having diameters of .175 in. and .125 in. immediattely above and below the shoulder 35, respectively, and a plunger member 39 whose diameter is .158 in. will provide the following operating characteristics for the injector:

First stagevalve opening pressure =2,462 p.s.i. First stagevalve closing pressure =1,206 p.s.i. Second stagevalve opening and closing pressure =l0,117 p.s.i.

From the time of opening of the second stage spray holes, to the end of travel of the piston valve, the injection pressure in the system is governed by the spring force, the difference in diameters of the piston valve and plunger, the effective spray hole areas of the first and second stage holes 26 and 28, and the contour of the engine driven cam (not shown) which operates the pump plunger 5.

The injector as described in accordance with my invention has the further important feature that the limited fuel volume in the spray tip cavity 25 tends to minimize after-dribbling of fuel when the piston valve is closed on its seat 27.

While only a single preferred embodiment of the invention has been disclosed, it is appreciated that numerous minor changes in the construction and arrangement of the parts may be made without departing from the spirit and scope of the invention as defined in the following claims.

I claim:

1. In a pressure fluid injector, a valve body having a bore and an injection fluid inlet to said bore, a valve in said bore and movable in one direction in said bore in response to inlet fluid pressure in the bore, said bore having a plurality of injection fluid outlets so located as v to be normally blocked by the valve and to be sequentially uncovered by the valve during its movement in said direction, resilient means opposing movement of the valve in said direction, a passage connected to said inlet and a member positioned in said valve body and in the path of travel of said valve during its movement in said direction, said member being normally spaced from said valve by a gap of predetermined extent and operatively engageable and movable by the valve only after an initial movement of said predetermined extent of the valve 4, in said direction, said member having an effective area reacted upon by inlet fluid pressure in said passage in opposition to movement of the member by the valve, said effective area being smaller than that over which said inlet fluid pressure in said bore acts on the valve in effecting movement of the valve in said direction.

2. In a pressure fluid injector, a valve body having a bore and an injection fluid inlet to said how, a valve in said bore and movable in one direction in said bore in response to inlet fluid pressure in the bore, said bore having a plurality of injection fluid outlets so located as to be normally blocked by the valve and to be sequentially uncovered by the valve during its movement in said direction, resilient means opposing movement of the valve in said direction, a passage connected to said inlet and a member positioned in said valve body and in the path of travel of said valve during its movement in said direction, said member being spaced from said valve by a gap of predetermined extent and arranged for engagement by and movement with the valve only after an initial movement of said predetermined extent of the valve in said direction, said member having an effective area reacted upon by inlet fluid pressure in said passage in opposition to movement of the member by the valve, said effective area being smaller than that over which said inlet fluid pressure in said bore acts on the valve in effecting valve movement beyond said predetermined extent.

3. The invention of claim 2, wherein one of said outlets is located to be uncovered by the valve during its said predetermined extent of movement, and wherein another of said outlets is located so as to remain covered by the valve pending its further movement in said direction.

4. In a two-stage injection device, a piston valve body having a bore, a passage for conducting fluid under pressure and terminating with an inlet to said bore, a cavity opposite one end of the bore, a piston valve seat defining the entrance to the cavity from the bore, a first stage injection outlet from said cavity and a second stage injection outlet from said bore, a piston valve slidable in the bore and normally blocking said second stage outlet, said piston valve having a portion engageable with said seat to close off said cavity from the bore, said second stage outlet being located to be uncovered by the piston valve when said portion is displaced a predetermined distance ay from said seat, said piston valve having a surface in continuous communication with the inlet fluid pressure in the bore adjacent the inlet and reactive to said fluid pressure for efiecting movement of the piston valve away from its seat, resilient means opposing said movement of the piston valve, and a member positioned in said valve body and in the path of travel of said valve during its movement away from its seat, said member being spaced from said valve by a gap of predetermined extent and arranged for engagement by and movement with the piston valve only after an initial movement of said predetermined extent of the piston valve away from its seat, said predetermined extent of movement being less than sufficient to uncover said second stage outlet, said member having a surface communicating with said passage and reacting to inlet fluid pressure therein in opposition to movement of the member with the piston valve, said member surface being of smaller area than the combined areas of said piston valve surface and seat engageable portion.

5. The invention of claim 4, together with a stop limiting movement of said member in the piston valve opening direction and defining, in part, said passage.

6. In a two-stage injection device, a piston valve body having a bore, a passage for conducting fluid under pressure and terminating with an inlet to said bore, a cavity opposite one end of the bore, a piston valve seat defining the entrance to the cavity from the bore, a first stage injection putlet from said pavity and a second stage injection outlet from said bore, a piston valve slidable inthe bore and normally blocking said second stage outlet, said piston having, a reduced end portion engageable with said seat to close ofI" said cavity from the bore, a shoulder on the piston valve spaced axially thereof from said reduced end portion, said shoulder being in continuous communication with the inlet fluid pressure in the bore adjacent the inlet and reactive to said fluid pressure in the bore for eflecting movement of the piston valve away from its seat, said second stage injection outlet being located to be uncovered by said shoulder after a predetermined movement of the piston valve away [from its seat, resilient means opposing said movement of the piston valve, and a member positioned in said valve body in the path of travel of said valve during its movement away from said seat and having an area exposed to said passage whereby said member is biased by fluid pressure in the passage into opposing relation with said piston valve movement, said member being spaced from the piston valve by a gap of predetermined extent and engageable by and movable with the piston valve only after an initial movement of said predetermined extent of the piston valve in opposition to said resilient means, said shoulder and reduced end portion of the piston valve having a greater combined fluid pressure responsive area than the fluid pressure biasing area of the member.

7. In a two-stage injector, means defining a bore having first and second stage injection outlets and an inlet for injection fluid under pressure, a first member in said bore controlling fluid flow out said outlets, said member having a surface in communication with said inlet Whereby increasing inlet fluid pressure serves to move the memher in one direction longitudinally of the bore to sequentia-lly open said outlets, an inlet fluid supply passage, and a second member positioned in said valve body and in the path of travel of said valve during its movement in said direction, said member being spaced from said valve by a gap of predetermined extent and thereby having a lost motion connection with the first member and movable thereby after said lost motion is taken up, said second member having an effective area reacted upon by inlet fluid pressure in said passage in opposition to movement of the second member by the first member, said effective area being smaller than that over which said first member surface is movably responsive to said pressure, said lost motion being taken up upon movement of the first member in said direction to a position inter mediate the opening of said first stage outlet and the opening of said second stage outlet.

References Cited in the file of this patent UNITED STATES PATENTS 1,814,443 Goldberg July 14, 1931 1,833,080 Kenworthy Nov. 24, 1931 2,144,861 Truxe'll Jan. 24, 1939 

